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Consumptive Water Use from Electricity Generation in the Southwest under Alternative Climate, Technology and Policy Futures
Abstract
This research assesses climate, technological, and policy impacts on consumptive water use from electricity generation in the Southwest over a planning horizon of nearly a century. We employed an integrated modeling framework taking into account feedbacks between climate change, air temperature and humidity, and consequent power plant water requirements. These direct impacts of climate change on water consumption by 2095 differ with technology improvements, cooling systems, and policy constraints, ranging from a 3%-7% increase over scenarios that do not incorporate ambient air impacts. Upon changing additional factors that alter electricity generation, water consumption increases by up to 8% over the reference scenario by 2095. With high penetration of wet-recirculating cooling, consumptive water required for low-carbon electricity generation via fossil fuels will likely exacerbate regional water pressure as droughts become more common and population increases. Adaptation strategies to lower water use include the use of advanced cooling technologies and greater dependence on solar and wind. Water consumption may be reduced by 50% in 2095 from the reference, requiring an increase in dry cooling shares to 35-40%. Alternatively, the same reduction could be achieved through photovoltaic and wind power generation constituting 60% of the grid, consistent with an increase of over 250% in technology learning rates.
... This would also lead to further underestimates in dry-season WI, 20 WC, and the associated risk. A power plant operation modeling tool called the Integrated Environmental Control Model (IECM) 28−30 shows the potential to simulate variable WIs over periods by considering the temporal variability of ambient climate conditions 31 in addition to plant characteristics. ...
... The water system module embedded in the IECM estimates cooling water consumption at power plants based on mass and energy balances with the inputs such as fuel type, cooling technology, and ambient climate conditions. IECM has been used extensively in previous studies 29,31,41,42,43 to estimate the water use at various stages of the entire fuel life cycle. In this study, we focus on the plant operation stage involving cooling water consumption that usually accounts for more than 90% 43 of the total life-cycle water consumption. ...
... One of the advantages of the IECM is its capability to consider the impacts of ambient climate conditions, that is, air temperature and relative humidity, 31 on the performance of the wet cooling tower and the associated WI. WI is projected to increase by 5% ∼ 10% by the end of this century because of climate change. ...
Previous studies have estimated power plant cooling water consumption based on the long-term average cooling water consumption intensity (WI: water consumption per unit of electricity generation) at an annual scale. However, the impacts of the seasonality of WI and streamflow on electricity generation are less well understood. In this study, a risk assessment method is developed to explore the seasonal risk of water-electricity nexus based on the Integrated Environmental Control Model, which can simulate variable WIs in response to daily weather conditions and avoid underestimation in WIs as well as nexus risk during dry seasons. Three indicators, reliability, maximum time to recovery, and total power generation loss, are proposed to quantify the seasonal nexus risk under water consumption policy constraint represented by the allowed maximum percentage of water consumption to streamflow. The applications of the method in two representative watersheds demonstrate that the nexus risk is highly seasonal and is greatly impacted by the seasonal variability of streamflow rather than annual average water resources conditions on which most previous studies are based. The nexus is found more risky in the watershed with almost double mean annual streamflow and greater streamflow variability, compared with the watershed with less streamflow variability.
... The literature examining the water-energy nexus over the past decade has grown substantially, with a focus on electricity generation constraints due to impacts of climate change and water stress [5,[9][10][11][12][13][14][15][16]. Assuming the same electricity generation profile of today, it has been estimated that water consumption in the southwest US will increase 3%-7% by 2095 [17]. However, rapid changes in the electricity sector, including increased utilization of wind and photovoltaic energy, along with retrofits of thermal plants with dry cooling systems, suggests that water consumption could rather decrease by up to 50% [17]. ...
... Assuming the same electricity generation profile of today, it has been estimated that water consumption in the southwest US will increase 3%-7% by 2095 [17]. However, rapid changes in the electricity sector, including increased utilization of wind and photovoltaic energy, along with retrofits of thermal plants with dry cooling systems, suggests that water consumption could rather decrease by up to 50% [17]. ...
... Recent reports examining the threats that climate change pose to the future US economy highlight the reduction in CO 2 emissions that could be achieved by decommissioning coal plants [8,12,[17][18][19][20]. Nonetheless, with natural gas becoming the predominant energy source for the electricity sector, the intensification of shale gas production in the US, and the significant increase in the intensity of water consumption of this process [21], raises questions about the implications of the transition from coal to natural gas on water availability. ...
The transition from coal to natural gas and renewables in the electricity sector and the rise of unconventional shale gas extraction are likely to affect water usage throughout the US. While new natural-gas power plants use less water than coal-fired power plants, shale gas extraction through hydraulic fracturing has increased water utilization and intensity. We integrated water and energy use data to quantify the intensity of water use in the US throughout the electricity’s lifecycle. We show that in spite of the rise of water use for hydraulic fracturing, during 2013–2016 the overall annual water withdrawal (8.74 × 10 ¹⁰ m ³ ) and consumption (1.75 × 10 ⁹ m ³ ) for coal were larger than those of natural gas (4.55 × 10 ¹⁰ m ³ , and 1.07 × 10 ⁹ m ³ , respectively). We find that during this period, for every MWh of electricity that has been generated with natural gas instead of coal, there has been a reduction of ∼1 m ³ in water consumption and ∼40 m ³ in water withdrawal. Examining plant locations spatially, we find that only a small proportion of net electricity generation takes place in water stressed areas, while a large proportion of both coal (37%) and natural gas (50%) are extracted in water stressed areas. We also show that the growing contribution of renewable energy technologies such as wind and solar will reduce water consumption at an even greater magnitude than the transition from coal to natural gas, eliminating much of water withdrawals and consumption for electricity generation in the US.
... Thus, strategies and systems for an efficient condenser's cooling with significantly reduced water consumption are particularly relevant to make electricity production and local population activities coexist [7,8]. Classic solutions include the use of dry heat exchanger (no water consumption with a significant loss of turbine efficiency, especially with high ambient temperatures, [5] and optimization of air-water hybrid systems such as plume abatement in wet tower (− 5 to 10% in water consumption [5]), Heller sprayed heat-exchanger (− 50 to − 75% in water consumption [9]) or combined wet and dry heat exchangers [10]. ...
... Classic solutions include the use of dry heat exchanger (no water consumption with a significant loss of turbine efficiency, especially with high ambient temperatures, [5] and optimization of air-water hybrid systems such as plume abatement in wet tower (− 5 to 10% in water consumption [5]), Heller sprayed heat-exchanger (− 50 to − 75% in water consumption [9]) or combined wet and dry heat exchangers [10]. Talati et al. [7] studied the longer-term alternatives to thermodynamic plants with wet cooling and showed that a massive use of photovoltaic, wind power or dry cooling would be efficient for the reduction of the water consumption in the years 2050-2095. However, dry cooling has several drawbacks: first, the heat transfer with air is poor compared to water, then, the circulation cost by compression is much higher than by pumping, and finally, dry air temperature in arid regions varies consequently between wintertime and summertime, but also between day and night [5]. ...
A novel storage concept, based on the coupling of heat and humidity storages, is presented and experimentally characterized. This coupled storage is aiming at optimizing the cooling of the condenser for CSP power plant, and more broadly, for any thermodynamic cycles devoted to the production of electricity from heat. The global system consists in a dual-media thermocline-like TES using humid air as heat transfer fluid and filled with a mixture of glass spheres and sorbent pebbles. Experimental campaigns have confirmed the validity of the concept, i.e. cold temperature and humidity can be stored in a solid matrix during the night and can be used later, to cool ambient air during the day, thanks to heat convection and moisture desorption. Characterization and understanding of the behaviour of this coupled storage are provided through temperature profiles, steam molar fraction and mass of water sorbed/desorbed. Results highlight that such storage can be effective to reduce the drop of performances for air-cooled condenser under high temperatures ambient, which occurs typically for CSP power plant in arid regions.
... water demand by thermoelectric plants in the Southwest is projected to increase 8% by 2100. 345 In a 10-year drought, summer electric generating potential in the Southwest could fall 3% to 9% under higher emissions (SRES A2) or 1% to 7% under lower emissions (SRES B1; Figure 25.8). 346 Any increase in water requirements for energy generation from fossil fuels would coincide with reduced water supply reliability from projected decreases in snowpack 46,77 and earlier snowmelt. ...
... conversion of two-thirds of fossil fuel plants to renewables would reduce water demand by half. 345 State energy policies are facilitating the switch to renewable energy. Arizona, California, Colorado, Nevada, and New Mexico have enacted renewable energy portfolio standards. ...
... Until now, energy−water nexus studies have focused on assessing the impacts of carbon mitigation strategies on water use in a single 8−10 or two 11 industrial sectors. Carbon mitigation could increase water consumption in the U.S. electric sector at both regional 12 and national 13 scales. But the impacts have high uncertainty due to the choice of energy sources and the cooling system, 14−16 e.g., the studies in China showed that carbon mitigation could promote renewable energy technologies and reduce water consumption in the power generation sector. ...
... Such trade-offs in water use may be exacerbated if high water use intensity technologies are used to reduce carbon emissions in the power generation sector. Water use intensity of the power generation is dependent on the choices of the cooling system and renewable energy penetration; 15,16,34 e.g., carbon mitigation may promote the adoption of high water use intensity technologies such as nuclear and coal-fired plants with carbon capture and storage (CCS) technology and thus increase total water use in the power generation sector, 12,14 although large-scale deployment of CCS technology is not possible in Shenzhen by 2030. In the study area, increasing the proportion of nuclear power may have cobenefits in water use since seawater is used for cooling in nuclear power generation. ...
Carbon mitigation strategies have been developed without sufficient consideration of their impacts on the water system. Here, our study evaluates whether carbon mitigation strategies would decrease or increase local industrial water use and water-related pollutants discharge by using a computable general equilibrium (CGE) model coupled with a water withdrawals and pollutants discharge module in Shenzhen, the fourth largest city in China. To fulfill China’s Nationally Determined Contributions (NDC) targets, Shenzhen’s GDP and welfare losses are projected to be 1.6% and 5.6% in 2030, respectively. The carbon abatement cost will increase from 56 USD/t CO2 in 2020 to 274 USD/t CO2 in 2030. The results reveal that carbon mitigation accelerates local industrial structure upgrading by restricting carbon-, energy-, and water-intensive industries, e.g., natural gas mining, non-metal, agriculture, food production, and textile sectors. Accordingly, carbon mitigation improves energy use efficiency and decreases 55% of primary energy use in 2030. Meanwhile, it reduces 4% of total industrial water use and 2.2-2.4% of two major pollutants discharge, i.e., CODCr and NH3-N. Carbon mitigation can also decrease petroleum (2.2%) and V-ArOH (0.8%) discharge but has negative impacts on most heavy metal(loid)s pollutants discharge (increased by -0.01% to 4.6%). These negative impacts are evaluated to be negligible on the environment. This study highlights the importance of considering the energy-water nexus for better-coordinated energy and water resources management at local and national levels.
... Furthermore, its co-benefits on air pollutant reduction (Dong et al., 2015) and health effects (Wu et al., 2017;Xie et al., 2016) have gained much attention recently. Recently, some energy-water nexus studies have been carried out to analyze the impacts of CO 2 mitigation strategies on energy use and water consumption in the power generation sector (Arent et al., 2014;Cameron et al., 2014;Chandel et al., 2011;Huang et al., 2017;Talati et al., 2016). These studies investigated water saving and CO 2 emission reduction under different CO 2 mitigation strategies and indicate that these strategies may increase or decrease water consumption due to the wide range of water use intensity of low-carbon emissions technologies choices (Kyle et al., 2013;Liu et al., 2015;Talati et al., 2016). ...
... Recently, some energy-water nexus studies have been carried out to analyze the impacts of CO 2 mitigation strategies on energy use and water consumption in the power generation sector (Arent et al., 2014;Cameron et al., 2014;Chandel et al., 2011;Huang et al., 2017;Talati et al., 2016). These studies investigated water saving and CO 2 emission reduction under different CO 2 mitigation strategies and indicate that these strategies may increase or decrease water consumption due to the wide range of water use intensity of low-carbon emissions technologies choices (Kyle et al., 2013;Liu et al., 2015;Talati et al., 2016). Also, there are increasingly integrated modeling tools considering the broader nexus of water, energy, and food system for CO 2 mitigation and climate adaptation purposes (Ermolieva et al., 2015;Howells et al., 2013;Kraucunas et al., 2015;Martinez-Hernandez et al., 2017). ...
Energy and water systems are interdependent and have complex dynamic interactions with the socioeconomic system and climate change. Few tools exist to aid decision-making regarding the management of water and energy resources at a watershed level. In this study, a Computable General Equilibrium (CGE) model and System Dynamics and Water Environmental Model (SyDWEM) were integrated (CGE-SyDWEM) to predict future energy use, CO 2 emissions, economic growth, water resource stress, and water quality change in a rapidly urbanizing catchment in China. The effects of both the CO 2 mitigation strategies and water engineering measures were evaluated. CO 2 mitigation strategies have the potential to reduce 46% CO 2 emissions and 41% energy use in 2025 compared with reference scenario. CO 2 mitigation strategies are also found to be effective in promoting industrial structure adjustment by decreasing the output of energy-and water-intensive industries. Accordingly, it can alleviate local water stress and improve water environment, including a 4.1% reduction in both domestic water use and pollutant emissions, a 16.8% water demand reduction in the labor-intensive industry sector, and 4.2% and 4.4% decrease in BOD 5 and NH 3-N loads in all industrial sectors, respectively. It is necessary to implement water engineering measures to further alleviate water resource stress and improve water quality. This study improves the understanding of the feedbacks of CO 2 abatement on water demand, pollutant discharges, and water quality improvement. The integrated model developed in this study can be used to aid energy, carbon, and water policy makers to understand the complicated synergistic effects of proposed CO 2 mitigation strategies on water demand and pollution emissions, and to design more effective policies and measures to ensure energy and water security in the future.
... For instance, water absorbed in the course of food preparation cannot be immediately accessible for any other use while bath water may be collected for further use, probably for flushing toilets or gardening purpose. The concept of consumptive water use is commonly used in agriculture (Liu et al., 2009;Zhang et al., 2019) and power production (Torcellini et al., 2003;Talati et al., 2016). In the other way, nonconsumptive use of water also constitutes part of domestic uses of water. ...
The existential value of water for human survival and sustenance prompted the need to determine factors responsible for water use efficiency (WUE) among twenty-seven households working in Bowen University, Iwo, Nigeria. The households were made up of academic and non-academic staff who, by virtue of their exposure and experience are knowledgeable enough to respond accurately to the insightful questions. Specialized variables of indoor water use were assessed using a structured questionnaire. Estimates of usedvolume of each variable/day were expressed in litres, the frequency of use and the sources of the used water were obtained. All respondents have tertiary education and are females. The family size ranged from 2 to 5 and they generally source their water (96.37% groundwater) close to their homes and premises. Potential areas of excessive water use in homes were identified, using Factor Analysis, to be laundry, incidental uses and auto-wash which are in the non-consumptive category. The trio constituted 53.33% of all water usage in homes. This is evidently beyond sustainability threshold and demands further attention. Thus, water use efficiency in homes should conservatively address non-consumptive uses by using water-propelled machines at full capacities, water-reuse/recycling and taking sensible responsibilities for resource sustainability.
... As shown in Fig. 7c, biofuels, including biodiesel and ethanol, contributed to 0.25-1.4% of total energy generation, but they consumed about 20% of water used for energy production in 2008. Studies showed that CCS technologies could increase water use for energy production by 29-81%, depending on fuels and cooling types (Ali, 2018;Sharma and Mahapatra, 2018;Talati et al., 2016). Stenzel et al. (2021) evaluated the impact of using BECCS on global water stress, and showed that irrigation of biomass plantations could exacerbate global water stress, which even exceeded the impact of climate change. ...
The increasing demand for water, energy, and food poses significant challenges to natural resources and environmental sustainability. The concept of water, environment, energy, and food (WEEF) nexus offers an opportunity for integrated management of WEEF systems. Emphasizing the role of water in achieving the sustainability of WEEF security, this study presents the competition of water use, withdrawal, and requirement in domestic sector, food production, and energy generation and how climate change impacts the water availability for food and energy production. The nexus challenge and solutions to maintain the sustainability of WEEF are discussed. Engineering measures, such as adopting new technologies (particularly more efficient irrigation technologies) to improve water and energy use efficiency, and non-engineering measures, such as dietary pattern shifts and food waste reduction, are suggested as possible approaches. To achieve acceptable, equitable, and adoptable sustainability of WEEF security, we also suggest that water resources management simultaneously consider social, environmental, economic, and technological factors.
... In addition, the use of CCS to capture and store carbon from thermal power plants can significantly increase water use. For example, the water consumption by plants equipped with CCS technologies increases by 29-81%, depending on the fuel types and cooling types (Ali 2018;Chandel et al. 2011;Sharma and Mahapatra 2018;Talati et al. 2016). Currently, global land use for biofuel production is about 30 Mha, of which 30% is equipped with irrigation. ...
Emphasizing the role of water in human and ecosystem sustainability, this study defines water security and its associated aspects. It then reflects on the availability of water, water supply, water demand, and water consumption. The question of water scarcity and crisis around the world is addressed next. What are the causes of water scarcity if it exists and how can it be ameliorated? How does climate change impact water scarcity? These are critical issues that need urgent attention, for their importance transcends scientific and engineering boundaries and directly affects the society.
... Studies also assessed the comparative assessment of coal and natural gas for water consumption and withdrawal rates based on plant cooling system, fuel extraction, and pollution control at individual plant level (Grubert et al., 2012). It is observed that recent studies are more concerned with predicting future scenarios of water uses (Feng et al., 2014;Qin et al., 2015;Talati et al., 2016), energy forecasting and planning with water constraints (Khan et al., 2016;Srinivasan et al., 2018), carbon emission constraints (Clemmer et al., 2013;Feng et al., 2014;Wang et al., 2013), and system cost minimization (Khan et al., 2018). It has been observed that most of these works refer to data from the USA (Qin et al., 2015) to assess the present and future water use for electricity generation. ...
Water use in coal power generation is one of the key points to highlight for the countries like India because country electricity demand increases rapidly which led to increase in water demand. The coal power sector in India will remain to be the dominant source of electricity generation until 2040 and will require a regular water supply, which is already in a stressful condition. This work focuses on the regional assessment of water withdrawal and consumption of the coal power sector at three broad stages includes fuel extraction, fuel preparation, and power generation. Our analysis reveals that 99% of the total water supply to the sector was withdrawn by power plants. Further, the study assessed its trade-off with other sectoral water demand adopting WSI (Water Stress Index) criteria for both surface and groundwater sources. The results highlighted the per capita groundwater to be under severe stress and similar status was also identified in the case of fresh surface water except for the Central region. The overall WSI status was found to be severe in all regions of India. This situation creates a water-scarce situation for water-guzzling power plants that are dependent on surface water and faces the competitive situation with the agriculture and domestic sector. Results of the study concluded that the technological up-gradation at the power plants could be helpful to reduce the total water demand by 78% of coal power sector which can be reduced the severity of regional water stress. Our study aids policymakers to identify the region which is more vulnerable in terms of cross-sectoral water demand and also fulfills the need for quality data availability at a regional scale that may use in the future towards sustainable water-resources management practices.
... As Figure 5e illustrates, water footprints of geothermal power technologies are obviously lower than for other methods. The reason for this can be explained: the conditions of air temperature and humidity constraint also have a large impact on water footprints [53]. Only relying on the conversion efficiency parameter would mislead the estimation. ...
Water use within power supply chains has been frequently investigated. A unified framework to quantify the water use of power supply chains deserves more development. This article provides an overview of the water footprint and virtual water incorporated into power supply chains. A water-use mapping model of the power supply chain is proposed in order to map the analysed research works according to the considered aspects. The distribution of water footprint per power generation technology per region is illustrated, in which Asia is characterised by the largest variation of the water footprint in hydro-, solar, and wind power. A broader consensus on the system boundary for the water footprint evaluation is needed. The review also concludes that the water footprint of power estimated by a top-down approach is usually higher and more accurate. A consistent virtual water accounting framework for power supply chains is still lacking. Water scarcity risks could increase through domestic and global power trade. This review provides policymakers with insights on integrating water and energy resources in order to achieve sustainable development for power supply chains. For future work, it is essential to identify the responsibilities of both the supply and demand sides to alleviate the water stress.
... Energy use, water consumption, and CO 2 emission are closely related to each other, so developing clean technologies to reduce CO 2 emission might demand more water (Talati et al., 2016). Policy makers need to set precise strategies about the usage of fossil sources of energy and water resources to mitigate the CO 2 emission (Anshasy and Katsaiti, 2014) and depletion of water reservoirs in order to provide sustainable energy and water services (Su et al., 2018). ...
Circular economy (CE) aims at sustainable development (SD) by focusing more on renewable sources of energy and precise management of waste to i) guarantee the secure access to resources, ii) combat climate change and global warming. Environmental issues arising from energy use and lack of policies to monitor them challenge sustainable development. Circular economy emphasizes the economic development with the least amount of undesirable environmental impacts. To evaluate the environmental performance of decision-making units (DMUs) with data envelopment analysis (DEA), this paper develops a common set of weights (CSW) model using the ideal point method. Therefore, energy and environmental efficiency of the organization for economic cooperation and development (OECD) countries is analyzed using the Malmquist productivity index (MPI) during 2012-2015. Although Switzerland has the highest energy and environmental efficiency during 2012-2014, findings indicate that Ireland and the USA have continuously improved their energy and environmental efficiency.
... Carbon capture and storage (CCS) heavily influences the water use of thermal power plants [69][70][71][72][73]. The water uses of CCS refer to the additional blue water used due to the addition of the CCS system. ...
Understanding the water use of power production is an important step to both a sustainable energy transition and an improved understanding of water conservation measures. However, there are large differences across the literature that currently present barriers to decision making. Here, the compiled inventory of the blue water use of power production from existing studies allowed to uncover the characteristics of water use and to investigate current uncertainties. The results show that photovoltaics, wind power, and run-of-the-river hydropower consume relatively little water, whereas reservoir hydropower and woody and herbaceous biomass can have an extremely large water footprint. The water consumption of power production can differ greatly across countries due to different geographic conditions. Only a few studies provided the values for the influencing factors of water use, such as the capacity factor. Values that are reported came mainly from assumptions and other literature rather than direct measurement. Omitting a life cycle stage may lead to significant underestimations. Water scarcity is attracting more attention, but the few existing results are not useable for a regional comparison due to data gaps and inconsistent measurements. In the future, a clear and detailed definition of the water footprint and system boundary of power production is essential to improving comparisons and energy systems modelling.
... • The water-energy nexus ( Ackerman and Fisher, 2013 ;Howells and Rogner, 2014 ;Talati et al., 2016 ; see also Chapters 23 , 25, and 31) inspired by the huge amounts of energy needed for water pumping or desalination and vice versa: the large amount of water needed in the energy sector, as illustrated by the impact a drought might have on electricity production; • Water-energy-land ( European Commission, 2012 ; Ringler et al., 2013;Senger and Spataru, 2015 ;Sharmina et al., 2016 ;Obersteiner et al., 2016 ; see also Chapters 16 , 22 and 26) all pointing to the manifold ecosystem services provided by land and the intersections with water, biomass, biodiversity, and energy; • Water-energy-mineral fertilizer ( Mo and Zhang, 2013 , see also Chapter 26 ) highlights the potential depletion of non-renewable natural resources (minerals), their relevance for food security, their complex supply chains with recycling and recovery opportunities from e.g. wastewater or agricultural residues, and the potential environmental risks from accumulation of these minerals via eutrophication; • Water-energy-minerals ( Giurco et al., 2014 ;Kleijn et al., 2011 : see also Chapters 18 , 19, 21, 24) as illustrated by the increasing intensity of water and energy use in mineral extraction processes with declining ore grades. ...
Demand for natural resources has grown rapidly for decades, and is expected to continue growing. These trends lead to repercussions, risks, and threats for humans and ecosystems at different scales. The challenges of sustainable resource management and governance are on numerous agendas, ranging from the G7 and G20 summits to UNEP’s International Resource Panel, World Economic Forum, SDG implementation, and a growing community of international scholars. Research highlights the importance of accounting for the interdependencies of resource use and sustainability goals such as eliminating hunger, mitigating climate change, and expanding energy access. There is a need to understand interdependencies and the feasibility of more integrated approaches. Debate is often framed in terms of a “nexus” between water, energy, and food (sometimes including other resources). The main aim of this handbook is to come to grips with what the nexus is about, provide a reference textbook with an overview, and a survey on emerging and cutting-edge research, and application of the concept. This handbook is edited by five dedicated scholars, drawing on different schools of thought from different continents. Assembling a wide group of more than 50 authors across a host of disciplines and interdisciplinary fields, this volume rests on a thorough review of relevant literature and, in emerging with a distinct and original perspective, it conceptualizes the resource nexus as a heuristic for understanding critical interlinkages between uses of different natural resources for systems of provision such as water, energy, and food. The editors organized a symposium which took place in London in March 2015, debating various aspects of the resource nexus and refining the concept and defining the structure of the handbook. All chapters have been reviewed several times.
... A few other basins in Western US and Central China also take additional responses in the agriculture sector, while both countries have a sizable power sector and the capacity to adapt in electricity generation. In particular, the potential of adapting through cooling-technology mainly exists in Central and Eastern US where most once-through cooling systems are currently installed; while water is already limited in Western US and there is little room to further reduce electricity water withdrawals over the century (Macknick et al 2012b, Averyt et al 2013, Liu et al 2015, Talati et al 2016. The California River basin, for instance, already has very small electricity water withdrawals and thus takes additional responses in agriculture to reduce irrigation water withdrawals by lowering crop production that mainly relies on irrigated agriculture (figure S8). ...
This paper explores regional response strategies to potential water scarcity. Using a model of integrated human-earth system dynamics (GCAM), we test a wide range of alternate water demand scenarios to explore regional response strategies. We create a typology that categorizes countries and basins according to their responses in electricity and agriculture to potential water scarcity. Three different categories are found. First, little response is observed for many basins because water demands do not increase enough to create scarcity. Second, the primary response is adjustments in the electricity sector (e.g. most basins in Western Europe, the United States and China) with a transition to water-saving cooling systems but marginal impact on total power generation or the fuel mix. Third, where there is a lack of sufficient responding capacity in the electricity sector (e.g. Pakistan, Middle East and several basins in India), additional response occurs through reduced irrigation water withdrawals, either by switching from domestic production to imports or from irrigated agriculture to rain-fed production. The primary response mechanism to demand-based water scarcity for individual basins is quite robust across the range of water demand scenarios tested. The results and typology in this paper will be valuable for future research exploring global water scarcity due to both demand and supply drivers.
... Much work on integrated energy supply planning has focused on the water use effects of investments in, or upgrades to new and existing generation capacity. Studies have used long-term energy modeling to examine the water use impacts of emissions reduction alternatives [10][11][12][13][14][15] or investigated the potential for reducing power sector water use by prioritizing less water-intensive technologies and cooling system retrofits [4,14,16,17] or fuel switching [18]. The use of dispatch protocols to achieve power-system water use objectives with an existing generation fleet is a dimension of water-energy policy that has garnered less attention. ...
... Taking into account impacts of climate change, there could be less inland freshwater available in many regions. The relation between future water use and thermoelectricity generation has been assessed in many regions, such as the southwest US (Talati et al., 2016), the UK (Murrant et al., 2017a) and South Africa (Thopil and Pouris, 2016). The scarcity of freshwater for cooling, as well as potentially in CO 2 capture units, in thermoelectric power plants can be expected in the near future (Murrant et al., 2017b). ...
Thermoelectric power plants traditionally have required huge volumes of water to condense steam from the turbine exhaust. The complex interdependency between water and energy poses new challenges for policy makers to achieve a safe, secure and sustainable supply of water and energy in the future. Cooling systems are the most water-intensive part of the thermoelectric generation process, presenting significant opportunities to reduce the withdrawal and consumptive use of fresh water. Reuse of impaired water for cooling can reduce freshwater withdrawal and decrease water contamination and withdrawal-related impacts on aquatic life and the environment. Here we focus on challenges and opportunities for improving water efficiency in the cooling systems of thermoelectric power plants. First, we present the types of cooling systems in a thermoelectric power plant. Then, we illustrate the key criteria for feed water quality for cooling systems. We use this information to determine appropriate design and operation guidelines for cooling systems. In order to facilitate the use of impaired water in cooling systems, we suggest the key technical issues and available water technologies for brackish water desalination. Keywords: Water consumption, Water withdrawal, Energy-efficient technology, Zero liquid discharge, Fit-for-purpose use
... A critical remaining analysis gap is a focus on population growth and resource demands, specifically under climate change [16][17][18][19][20][21][22][23][24] and in urban areas [84,85]. Critical areas of research include technologies and policies that enable less water-intensive energy sources and integration with new and existing critical infrastructure. ...
Purpose of Review
Water for the energy sector is an interdisciplinary challenge that requires new integrated systems knowledge, well-documented case studies that test various decision processes, and both quantitative and qualitative modeling and analyses to support sustainable decision-making. This review paper highlights water requirements of the energy sector and summarizes interdisciplinary research opportunities for sustainable and efficient management of water for energy, and new datasets to inform analysis of water policies and programs affecting energy systems.
Recent Findings
The energy sector depends closely on water resources for primary fuels production (including extraction or cultivation, processing, and refining) and electric power generation in thermoelectric and hydroelectric power plants. While research in these areas has advanced significantly in recent years, questions remain regarding water quality and quantity impacts of emerging technologies and policies in the water-energy sectors, potential for use of alternative water resources, impact of energy portfolio transitions, and tools to aid decision-making under uncertainty.
Summary
Water is essential for energy production and power generation processes. Projected transitions in energy portfolios and water for energy policy hold the potential to both mitigate or exacerbate water stress, therefore motivating a critical need for systems integration and analysis approaches that can guide the development of cost-effective, resource-efficient, and resilient systems and services.
... Our study implies that climate change itself is estimated to have less of an impact on thermoelectric power plants when compared to impacts presented in existing studies. Climate change mitigation policies will probably alleviate some of these adverse impacts 24 . Further, a majority of the power plants examined in this study are likely to be retired by the 2060s as the current US energy system is gradually transitioned from a fossil fuel-dominated structure to more of a mixture of renewable and non-renewable energy sources. ...
Previous modelling studies suggest that thermoelectric power generation is vulnerable to climate change, whereas studies based on historical data suggest the impact will be less severe. Here we explore the vulnerability of thermoelectric power generation in the United States to climate change by coupling an Earth system model with a thermoelectric power generation model, including state-level representation of environmental regulations on thermal effluents. We find that the impact of climate change is lower than in previous modelling estimates due to an inclusion of a spatially disaggregated representation of environmental regulations and provisional variances that temporarily relieve power plants from permit requirements. More specifically, our results indicate that climate change alone may reduce average generating capacity by 2–3% by the 2060s, while reductions of up to 12% are expected if environmental requirements are enforced without waivers for thermal variation. Our work highlights the significance of accounting for legal constructs and underscores the effects of provisional variances in addition to environmental requirements.
Energy and water resources function as the base for humans’ socioeconomic development, which are closely linked with each other in the production process. With the rapid economic development, the contradiction between the supply and demand of energy and water resources has become acute. Meanwhile, the carbon reduction goals further enhanced the energy and water constraints, which inevitably have a significant impact on economic growth. Exploring the effect of energy and water constraints on the economic growth under climate goals is essential for policy maker to minimize the economic loss during carbon control. To realize this aim, we introduced the modified Romers’ economic growth model to estimate the impact of energy-water constraints on economic growth based on relative data in 30 provinces in China from 2000 to 2019. Then the spatial-temporal characteristics of the energy-water drag effects on China’s economic growth have been analyzed. We further applied scenario analysis method to investigate the changes in growth drag effects of energy and water resources under carbon mitigation goals in 2025 and 2030. The results show that China’s economic growth rate was reduced by 7.72% and 7.99% during the study period due to energy and water resources constraints respectively. In terms of the temporal trend, the energy-water growth drag effect shows a downward trend as a whole during 2000–2019, and the growth drag of energy on economic growth is slightly greater than that of water resources. As to spatial distribution, regions with high constraint effects of energy and water on economic growth are mainly located in the East China, while some north regions feature low energy-water constraints. According to the simulation results, China’s energy-water drag effects on the economic growth are 6.85% and 7.03% respectively, under the baseline and strong carbon control scenarios, higher than the 6.53% under the weak carbon control. Based on this, this paper proposes to design targeted energy-water constraint strategies and promote production efficiency to achieve a win-win situation of economic development and dual-carbon goals.
Energy crises, water shortages, and rising carbon emissions are constantly posing new demands and challenges to global economic development. Considering the problem of high emissions and high water consumption in the process of energy production and transformation in resourcebased cities, this study established the LEAP-Jincheng model based on the low emissions analysis
platform (LEAP) model. Taking 2020 as the base year, the baseline scenario (BS), policy scenario (PS), and intensified scenario (IS) were set to predict future energy and water consumption and carbon
emissions of Jincheng from 2021 to 2050. The results show that both PS and IS can achieve energy conservation and emission reduction to some extent. The total energy consumption of PS will be 32.89 million metric tons of coal equivalent in 2050, 15.62% less than the BS. However, the carbon emissions in 2030 will reach 8221 metric tons CO2 equivalent, which is significantly higher than that in other scenarios. In PS, carbon emissions after 2030 will not be significantly reduced, and the energy–water elasticity coefficient is 0.77, which fails to achieve effective emission reduction under energy–water synergy. The total energy consumption of the IS will be 22.57 million metric tons of coal equities in 2050, which has a total decrease of 31.38%, compared to BS. In the IS, the carbon emissions will reach a peak in 2030 (68.77 million metric tons CO2 equivalent) and subsequently reduce to 50.72 million metric tons CO2 equivalent in 2050, which has a total decrease of 50.64%, compared to BS. Furthermore, water consumption and energy–water synergy results show that the elastic coefficient is 1.37 in the IS. The IS is the best scenario for Jincheng to achieve coordinated development of energy and water resources from a low-carbon perspective. This study can provide a scientific basis for decision-making departments of Jincheng to formulate targeted sustainable development policies for energy and water and has an essential promoting significance for China to achieve the “double carbon” goals.
Understanding water consumption is an important component of water management. However, water consumption data are limited and consumption coefficients do not account for variability through time and across users. This study combines federally maintained discharge data with state‐maintained withdrawal data at monthly time steps to estimate facility‐level and spatially aggregated water consumption in Virginia between 2010 and 2016. We evaluate (1) the feasibility of using discharge and withdrawal datasets to estimate sub‐annual water consumption, (2) how these consumption estimates vary depending on the level of spatial aggregation, and (3) what patterns of seasonality exist in consumption estimates. We find that a combined process of text matching and geospatial analysis is effective in matching facilities and yielding monthly time‐series of water consumption. Our results suggest that median consumption in industrial (17%) and commercial (19%) facilities may be higher than median consumption coefficients in the literature (10%). Consumption estimates also demonstrated more variability across facilities and seasons than aggregate coefficients in the literature suggest. Combining this approach with institutional knowledge can assist in quantifying issues such as inter‐basin transfers and infiltration that impact consumption estimates, ultimately allowing for more accurate accounts of water use and availability.
This study aims to simulate the economic and environmental effects of energy-carbon-water (ECW¹) policies in China. The main novelty works are to clarify the theoretical ECW nexus mechanism at macro-economic level and develop the ECW-CGE policy assessment model with ECW policy modules integrated. Using this model, isolated and integrated ECW policy scenarios are designed and simulated in 2050. Policy effectiveness and co-effects are further discussed. The main findings are: (1) For economic effects, GDP losses grow from 0.31% in water policy scenario W1 to 1.51% in integrated policy scenario ECW2. Energy and carbon emission policies cause greater outputs losses in energy and carbon intensive sectors, while water policy impacts stronger on agricultural and service sectors. (2) For environmental effects, integrated policy scenarios reduce the most of ECW, and isolated ones mainly affect their targeted ECW elements. (3) For policy effectiveness, isolated policy scenarios have greater individual effectiveness, integrated ones could balance overall ECW management. (4) Synergy and trade-off effects exist in all scenarios. Governance cooperation and differentiated sectoral policies are needed to realize sustainable development in ECW system. The main findings could inspire ECW management policy makings both for China and countries with similar environmental constraints.
Water availability plays an important role in the expansion planning of utility-scale solar power plants, especially in the arid regions of the Middle East and North Africa. Although these power plants usually account for only a small fraction of local water demand, competition for water resources between communities, farmers, companies, and power suppliers is already emerging and is likely to intensify in future. Despite this, to date there has been a lack of comprehensive studies analyzing interdependencies and potential conflicts between energy and water at local level. This study addresses this research gap and examines the linkages between water resources and energy technologies at local level based on a case study conducted in Ouarzazate, Morocco, where one of the largest solar power complexes in the world was recently completed. To better understand the challenges faced by the region in light of increased water demand and diminishing water supply, a mixed-method research design was applied to integrate the knowledge of local stakeholders through a series of workshops. In a first step, regional socio-economic water demand scenarios were developed and, in a second step, water saving measures to avoid critical development pathways were systematically evaluated using a participatory multi-criteria evaluation approach. The results are a set of water demand scenarios for the region and a preferential ranking of water saving measures that could be drawn upon to support decision-making relating to energy and water development in the region.
Electricity generation requires water. With the global demand for electricity expected to increase significantly in the coming decades, the water demand in the power sector is also expected to rise. However, due to the ongoing global energy transition, the future structure of the power supply—and hence future water demand for power generation—is subject to high levels of uncertainty, because the volume of water required for electricity generation varies significantly depending on both the generation technology and the cooling system. This study shows the implications of ambitious decarbonization strategies for the direct water demand for electricity generation. To this end, water demand scenarios for the electricity sector are developed based on selected global energy scenario studies to systematically analyze the impact up to 2040. The results show that different decarbonization strategies for the electricity sector can lead to a huge variation in water needs. Reducing greenhouse gas emissions (GHG) does not necessarily lead to a reduction in water demand. These findings emphasize the need to take into account not only GHG emission reductions, but also such aspects as water requirements of future energy systems, both at the regional and global levels, in order to achieve a sustainable energy transition.
As one of the most developed provinces in China, Jiangsu province is facing both energy and water stresses. The impact of energy production on water resource remains to be seen, especially in terms of a changing climate. In this study, we adopt a Long-range Energy Alternatives Planning System (LEAP) model combined with plant-level data to study the impact of energy policies on water resources management. The results indicate that energy efficiency improvements and industry structure optimization can result in 40% and 33% water withdrawal savings respectively in the future depending on the level of optimization. With several integrated measures, total water use can meet the 2030 targets set by the Jiangsu provincial government. Shifts in cooling technology can bring significant water-savings benefits and help fulfill water use-control targets. Furthermore, we find that the Suzhou and Xuzhou administrative areas will experience power output efficiency reductions and will need more water in 2030 under the RCP45 and RCP85 scenarios. More efforts are needed to mitigate climate change and offset its negative impact on energy and water resource. The results of this study will be informative for both resource management and policy design.
This report provides estimates of operational water withdrawal and water consumption factors for electricity generating technologies in the United States. Estimates of water factors were collected from published primary literature and were not modified except for unit conversions. The water factors presented may be useful in modeling and policy analyses where reliable power plant level data are not available. Major findings of the report include: water withdrawal and consumption factors vary greatly across and within fuel technologies, and water factors show greater agreement when organized according to cooling technologies as opposed to fuel technologies; a transition to a less carbon-intensive electricity sector could result in either an increase or a decrease in water use, depending on the choice of technologies and cooling systems employed; concentrating solar power technologies and coal facilities with carbon capture and sequestration capabilities have the highest water consumption values when using a recirculating cooling system; and non-thermal renewables, such as photovoltaics and wind, have the lowest water consumption factors. Improved power plant data and further studies into the water requirements of energy technologies in different climatic regions would facilitate greater resolution in analyses of water impacts of future energy and economic scenarios. This report provides the foundation for conducting water use impact assessments of the power sector while also identifying gaps in data that could guide future research.
Significance
Devising sustainable climate change mitigation policies with attention to potential synergies and constraints within the climate–energy–water nexus is the subject of ongoing integrated modeling efforts. This study employs a regional integrated assessment model and a regional Earth system model at high spatial and temporal resolutions in the Unites States to compare the implications of two of the representative concentration pathways under consistent socioeconomics. The results clearly show, for the first time to our knowledge, that climate change mitigation policies, if not designed with careful attention to water resources, could increase the magnitude, spatial coverage, and frequency of water deficits. The results challenge the general perception that mitigation that aims at reducing warming also would alleviate water deficits in the future.
Climate change may constrain future electricity generation capacity by increasing the incidence of extreme heat and drought events. We estimate reductions to generating capacity in the Western United States based on long-term changes in streamflow, air temperature, water temperature, humidity and air density. We simulate these key parameters over the next half-century by joining downscaled climate forcings with a hydrologic modelling system. For vulnerable power stations (46% of existing capacity), climate change may reduce average summertime generating capacity by 1.1-3.0%, with reductions of up to 7.2-8.8% under a ten-year drought. At present, power providers do not account for climate impacts in their development plans, meaning that they could be overestimating their ability to meet future electricity needs.
The power sector withdraws more freshwater annually than any other sector in the US. The current portfolio of electricity generating technologies in the US has highly regionalized and technology-specific requirements for water. Water availability differs widely throughout the nation. As a result, assessments of water impacts from the power sector must have a high geographic resolution and consider regional, basin-level differences. The US electricity portfolio is expected to evolve in coming years, shaped by various policy and economic drivers on the international, national and regional level; that evolution will impact power sector water demands. Analysis of future electricity scenarios that incorporate technology options and constraints can provide useful insights about water impacts related to changes to the technology mix. Utilizing outputs from the regional energy deployment system (ReEDS) model, a national electricity sector capacity expansion model with high geographical resolution, we explore potential changes in water use by the US electric sector over the next four decades under various low carbon energy scenarios, nationally and regionally.
In 2007 the US Congress began considering a set of bills to implement a cap-and-trade system to limit the nation's greenhouse gas (GHG) emissions. The MIT Integrated Global System Model (IGSM)—and its economic component, the Emissions Prediction and Policy Analysis (EPPA) model—were used to assess these proposals. In the absence of policy, the EPPA model projects a doubling of US greenhouse gas emissions by 2050. Global emissions, driven by growth in developing countries, are projected to increase even more. Unrestrained, these emissions would lead to an increase in global CO2 concentration from a current level of 380 ppmv to about 550 ppmv by 2050 and to near 900 ppmv by 2100, resulting in a year 2100 global temperature 3.5–4.5°C above the current level. The more ambitious of the Congressional proposals could limit this increase to around 2°C, but only if other nations, including developing countries, also strongly controlled greenhouse gas emissions. With these more aggressive reductions, the economic cost measured in terms of changes in total welfare in the United States could range from 1.5% to almost 2% by the 2040–2050 period, with 2015 CO2-equivalent prices between 55, rising to between 210 by 2050. This level of cost would not seriously affect US GDP growth but would imply large-scale changes in its energy system.
This paper summarizes the development process and main characteristics of the Representative Concentration Pathways (RCPs), a set of four new scenarios developed for the climate modeling community as a basis for long-term and near-term modeling experiments. The four RCPs together span the range of year 2100 radiative forcing values found in the open literature, i.e. from 2.6 to 8.5 W/m2. The RCPs are the product of an innovative collaboration between integrated assessment modelers, climate modelers, terrestrial ecosystem modelers and emission inventory experts. The resulting product forms a comprehensive data set with high spatial and sectoral resolutions for the period extending to 2100. Land use and emissions of air pollutants and greenhouse gases are reported mostly at a 0.5 x 0.5 degree spatial resolution, with air pollutants also provided per sector (for well-mixed gases, a coarser resolution is used). The underlying integrated assessment model outputs for land use, atmospheric emissions and concentration data were harmonized across models and scenarios to ensure consistency with historical observations while preserving individual scenario trends. For most variables, the RCPs cover a wide range of the existing literature. The RCPs are supplemented with extensions (Extended Concentration Pathways, ECPs), which allow climate modeling experiments through the year 2300. The RCPs are an important development in climate research and provide a potential foundation for further research and assessment, including emissions mitigation and impact analysis.
Representative Concentration Pathway (RCP) 4.5 is a scenario that stabilizes radiative forcing at 4.5 W m−2 in the year 2100 without ever exceeding that value. Simulated with the Global Change Assessment Model (GCAM), RCP4.5 includes long- term, global emissions of greenhouse gases, short-lived species, and land-use-land-cover in a global economic framework. RCP4.5 was updated from earlier GCAM scenarios to incorporate historical emissions and land cover information common to the RCP process and follows a cost-minimizing pathway to reach the target radiative forcing. The imperative to limit emissions in order to reach this target drives changes in the energy system, including shifts to electricity, to lower emissions energy technologies and to the deployment of carbon capture and geologic storage technology. In addition, the RCP4.5 emissions price also applies to land use emissions; as a result, forest lands expand from their present day extent. The simulated future emissions and land use were downscaled from the regional simulation to a grid to facilitate transfer to climate models. While there are many alternative pathways to achieve a radiative forcing level of 4.5 W m−2, the application of the RCP4.5 provides a common platform for climate models to explore the climate system response to stabilizing the anthropogenic components of radiative forcing.
The sustainability of water resources in future decades is likely to be affected by increases in water demand due to population growth, increases in power generation, and climate change. This study presents water withdrawal projections in the United States (U.S.) in 2050 as a result of projected population increases and power generation at the county level as well as the availability of local renewable water supplies. The growth scenario assumes the per capita water use rate for municipal withdrawals to remain at 2005 levels and the water use rates for new thermoelectric plants at levels in modern closed-loop cooling systems. In projecting renewable water supply in future years, median projected monthly precipitation and temperature by sixteen climate models were used to derive available precipitation in 2050 (averaged over 2040-2059). Withdrawals and available precipitation were compared to identify regions that use a large fraction of their renewable local water supply. A water supply sustainability risk index that takes into account additional attributes such as susceptibility to drought, growth in water withdrawal, increased need for storage, and groundwater use was developed to evaluate areas at greater risk. Based on the ranking by the index, high risk areas can be assessed in more mechanistic detail in future work.
Current scientific knowledge on the future response of the climate system to human-induced perturbations is comprehensively captured by various model intercomparison efforts. In the preparation of the Fourth Assessment Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC), intercomparisons were organized for atmosphere-ocean general circulation models (AOGCMs) and carbon cycle models, named "CMIP3" and "C4MIP", respectively. Despite their tremendous value for the scientific community and policy makers alike, there are some difficulties in interpreting the results. For example, radiative forcings were not standardized across the various AOGCM integrations and carbon cycle runs, and, in some models, key forcings were omitted. Furthermore, the AOGCM analysis of plausible emissions pathways was restricted to only three SRES scenarios. This study attempts to address these issues. We present an updated version of MAGICC, the simple carbon cycle-climate model used in past IPCC Assessment Reports with enhanced representation of time-varying climate sensitivities, carbon cycle feedbacks, aerosol forcings and ocean heat uptake characteristics. This new version, MAGICC6, is successfully calibrated against the higher complexity AOGCMs and carbon cycle models. Parameterizations of MAGICC6 are provided. The mean of the emulations presented here using MAGICC6 deviates from the mean AOGCM responses by only 2.2% on average for the SRES scenarios. This enhanced emulation skill in comparison to previous calibrations is primarily due to: making a "like-with-like comparison" using AOGCM-specific subsets of forcings; employing a new calibration procedure; as well as the fact that the updated simple climate model can now successfully emulate some of the climate-state dependent effective climate sensitivities of AOGCMs. The diagnosed effective climate sensitivity at the time of CO2 doubling for the AOGCMs is on average 2.88 °C, about 0.33 °C cooler than the mean of the reported slab ocean climate sensitivities. In the companion paper (Part 2) of this study, we examine the combined climate system and carbon cycle emulations for the complete range of IPCC SRES emissions scenarios and the new RCP pathways.
The Power of Green
Carbon dioxide is produced both by fossil fuel burning and by deforestation and other land-use changes. Limiting both sources of CO 2 is necessary if we are to curb global warming. Wise et al. (p. 1183 ) use an integrated assessment model to explore the consequences of limiting atmospheric CO 2 concentrations at levels between 450 and 550 parts per million through a combination of fossil-fuel emissions reductions and land-use modification. Land-use modification strategies reduce the cost of limiting atmospheric CO 2 concentrations, but can make crop prices rise and transform human diets, for example, when people consume less beef and other carbon-intensive protein sources. The rate at which crop productivity is improved has a strong influence on emissions from land-use change. Thus, the technology used for growing crops is potentially as important for limiting atmospheric CO 2 as are approaches like CO 2 capture and storage.
Regional or local climate change modeling studies currently require starting with a global climate model, then downscaling to the region of interest. How should global models be chosen for such studies, and what effect do such choices have? This question is addressed in the context of a regional climate detection and attribution (D&A) study of January-February-March (JFM) temperature over the western U.S. Models are often selected for a regional D&A analysis based on the quality of the simulated regional climate. Accordingly, 42 performance metrics based on seasonal temperature and precipitation, the El Nino/Southern Oscillation (ENSO), and the Pacific Decadal Oscillation are constructed and applied to 21 global models. However, no strong relationship is found between the score of the models on the metrics and results of the D&A analysis. Instead, the importance of having ensembles of runs with enough realizations to reduce the effects of natural internal climate variability is emphasized. Also, the superiority of the multimodel ensemble average (MM) to any 1 individual model, already found in global studies examining the mean climate, is true in this regional study that includes measures of variability as well. Evidence is shown that this superiority is largely caused by the cancellation of offsetting errors in the individual global models. Results with both the MM and models picked randomly confirm the original D&A results of anthropogenically forced JFM temperature changes in the western U.S. Future projections of temperature do not depend on model performance until the 2080s, after which the better performing models show warmer temperatures.
Hydropower and thermoelectric power together contribute 98% of the worldâ €™ s electricity generation at present. These power-generating technologies both strongly depend on water availability, and water temperature for cooling also plays a critical role for thermoelectric power generation. Climate change and resulting changes in water resources will therefore affect power generation while energy demands continue to increase with economic development and a growing world population. Here we present a global assessment of the vulnerability of the worldâ €™ s current hydropower and thermoelectric power-generation system to changing climate and water resources, and test adaptation options for sustainable water-energy security during the twenty-first century. Using a coupled hydrological-electricity modelling framework with data on 24,515 hydropower and 1,427 thermoelectric power plants, we show reductions in usable capacity for 61-74% of the hydropower plants and 81-86% of the thermoelectric power plants worldwide for 2040-2069. However, adaptation options such as increased plant efficiencies, replacement of cooling system types and fuel switches are effective alternatives to reduce the assessed vulnerability to changing climate and freshwater resources. Transitions in the electricity sector with a stronger focus on adaptation, in addition to mitigation, are thus highly recommended to sustain water-energy security in the coming decades.
This study employs a power plant modeling tool to explore the feasibility of reducing unit-level emission rates of CO2 by 30% by retrofitting carbon capture, utilization, and storage (CCUS) to existing U.S. coal-fired electric generating units (EGUs). Our goal is to identify feasible EGUs and their key attributes. The results indicate that for about 60 gigawatts of the existing coal-fired capacity, the implementation of partial CO2 capture appears feasible, though its cost is highly dependent on the unit characteristics and fuel prices. Auxiliary gas-fired boilers can be employed to power a carbon capture process without significant increases in the cost of electricity generation. A complementary CO2 emission trading program can provide additional economic incentives for the deployment of CCS with 90% CO2 capture. Selling and utilizing the captured CO2 product for enhanced oil recovery can further accelerate CCUS deployment and also help reinforce a CO2 emission trading market. These efforts would allow existing coal-fired EGUs to continue to provide a significant share of the U.S. electricity demand.
Abstract Water withdrawal for electricity generation in the United States accounts for approximately half the total freshwater withdrawal. With steadily growing electricity demands, a changing climate, and limited water supplies in many water-scarce states, meeting future energy and water demands poses a significant socioeconomic challenge. Employing an integrated modeling approach that captures the energy–water interactions at regional and national scales can improve our understanding of the key drivers that govern those interactions and the role of national policies. In this study, the Global Change Assessment Model (GCAM), a technologically-detailed integrated model of the economy, energy, agriculture and land use, water, and climate systems, was extended to model the electricity and water systems at the state level in the U.S. (GCAM-USA). GCAM-USA was employed to estimate future state-level electricity generation and consumption, and their associated water withdrawals and consumption under a set of seven scenarios with extensive detail on the generation fuel portfolio, cooling technology mix, and their associated water use intensities. These seven scenarios were explored to investigate the implications of socioeconomic development and growing electricity demands, cooling system transitions, adoption of water-saving technologies, climate mitigation policy and electricity trading options on future water demands of the U.S. electric-sector. Our findings include: 1) decreasing water withdrawals and increasing water consumption from the conversion from open-loop to closed-loop cooling systems; 2) different energy-sector water demand behaviors with alternative pathways to the mitigation goal; 3) open trading of electricity benefiting energy-scarce yet demand-intensive states; 4) across-state homogeneity under certain driving forces (e.g., climate mitigation and water-saving technologies) and mixed effects under other drivers (e.g.,, electricity trade); and 5) a clear trade-off between water consumption and withdrawal for the electricity sector in the U.S. The paper discusses this withdrawal–consumption trade-off in the context of current national policies and regulations that favor decreasing withdrawals (and increasing consumptive use), and the role of water-saving technologies. The study also clearly shows that climate mitigation strategies focusing on CCS and nuclear power will have less favorable water consumption effects than strategies that support renewable energy and water-saving technologies. The highly-resolved nature of this study, both geographically and technologically, provides a useful platform to address scientific and policy-relevant and emerging issues at the heart of the water–energy nexus in the U.S.
The most important energy development of the past decade has been
the wide deployment of hydraulic fracturing technologies that enable
the production of previously uneconomic shale gas resources in North
America. If these advanced gas production technologies were to be
deployed globally, the energy market could see a large influx of economically
competitive unconventional gas resources. The climate
implications of such abundant natural gas have been hotly debated.
Some researchers have observed that abundant natural gas substituting
for coal could reduce carbon dioxide (CO2) emissions. Others
have reported that the non-CO2 greenhouse gas emissions associated
with shale gas production make its life cycle emissions higher than
those of coal. Assessment of the full impact of abundant gas on
climate change requires an integrated approach to the global energy–
economy–climate systems, but the literature has been limited in either
its geographic scope9,10 or its coverage of greenhouse gases2. Here we
show that market-driven increases in global supplies of unconventional
natural gas do not discernibly reduce the trajectory of greenhouse
gas emissions or climate forcing. Our results, based on simulations
from five state-of-the-art integrated assessment models of energy–
economy–climate systems independently forced by an abundant gas
scenario, project large additional natural gas consumption of up to
+170 per cent by 2050. The impact on CO2 emissions, however, is
found to be much smaller (from -2 per cent to +11 per cent), and a
majority of the models reported a small increase in climate forcing
(from -0.3 per cent to +7 per cent) associated with the increased use
of abundant gas.Our results show that although market penetration
of globally abundant gas may substantially change the future energy
system, it is not necessarily an effective substitute for climate change
mitigation policy.
We employ an integrated systems modeling tool to assess the water impacts of the new source performance standards recently proposed by the U.S. Environmental Protection Agency for limiting CO2 emissions from coal- and gas-fired power plants. The implementation of amine-based carbon capture and storage (CCS) for 40% CO2 capture to meet the current proposal will increase plant water use by roughly 30% in supercritical pulverized coal-fired power plants. The specific amount of added water use varies with power plant and CCS designs. More stringent emission standards than the current proposal would require CO2 emission reductions for natural gas combined-cycle (NGCC) plants via CCS, which would also increase plant water use. When examined over a range of possible future emission standards from 1,100 to 300 lb CO2/MWh gross, new baseload NGCC plants consume roughly 60 to 70% less water than coal-fired plants. A series of adaptation approaches to secure low-carbon energy production and improve the electric power industry's water management in the face of future policy constraints are discussed both quantitatively and qualitatively.
The U.S. electric sector's reliance on water makes it vulnerable to climate variability and change. Here we investigate whether carbon mitigation policies would improve or exacerbate electric sector water reliance. We use EPAUS9r MARKAL to model changes in U.S. electric sector water withdrawal and consumption through 2055 resulting from energy system-wide CO2 emissions reduction targets of 10%, 25%, and 50%, as well as nine sensitivity analysis scenarios. CO2 reduction strategies accelerate the deployment of more water-efficient thermoelectric generation technologies and increase the use of renewables, nuclear, and carbon capture. The 50% CO2 reduction scenario also prompts electrification in end-use demand sectors, most notably transportation, increasing electricity demand 36% by 2055. In aggregate, CO2 reduction strategies decrease national electric sector water withdrawal in all scenarios (−31% to −46% by 2055), but have a varied impact on water consumption (−4% to +42% by 2055). These changes in electricity generation technology and the resulting change in water use would likely reduce electric sector vulnerability to droughts and heat waves.
Improving the energy efficiency of building stock, commercial equipment, and household appliances can have a major positive impact on energy use, carbon emissions, and building services. Sub-national regions such as the U.S. states wish to increase energy efficiency, reduce carbon emissions, or adapt to climate change. Evaluating sub-national policies to reduce energy use and emissions is difficult because of the large uncertainties in socioeconomic factors, technology performance and cost, and energy and climate policies. Climate change itself may undercut such policies. However, assessing all of the uncertainties of large-scale energy and climate models by performing thousands of model runs can be a significant modeling effort with its accompanying computational burden. By applying fractional-factorial methods to the GCAM-USA 50-state integrated-assessment model in the context of a particular policy question, this paper demonstrates how a decision-focused sensitivity analysis strategy can greatly reduce computational burden in the presence of uncertainty and reveal the important drivers for decisions and more detailed uncertainty analysis.
Water and energy resources are intrinsically linked, yet they are managed separately-even in the water-scarce American southwest. This study develops a spatially-explicit model of water-energy interdependencies in Arizona and assesses the potential for co-beneficial conservation programs. The interdependent benefits of investments in 8 conservation strategies are assessed within the context of legislated renewable energy portfolio and energy efficiency standards. The co-benefits of conservation are found to be significant. Water conservation policies have the potential to reduce statewide electricity demand by 0.82-3.1%, satisfying 4.1-16% of the state's mandated energy-efficiency standard. Adoption of energy-efficiency measures and renewable generation portfolios can reduce non-agricultural water demand by 1.9-15%. These conservation co-benefits are typically not included in conservation plans or benefit-cost analyses. Many co-benefits offer negative costs of saved water and energy, indicating that these measures provide water and energy savings at no net cost. Because ranges of costs and savings for water-energy conservation measures are somewhat uncertain, future studies should investigate the co-benefits of individual conservation strategies in detail. Although this study focuses on Arizona, the analysis can be extended elsewhere as renewable portfolio and energy efficiency standards become more common nationally and internationally.
The transition from the greenhouse gas (GHG) emission levels currently allowed under the Kyoto Protocol climate agreement to more ambitious, and internationally comprehensive, GHG reduction goals will have important implications for the global economic system. Given the major role that the United States plays in the global economy, and also as a major GHG emitter, this paper examines a range of climate policy pathways for the country in the context of international actions. The ADAGE model is used to examine policy impacts for climate scenarios, focusing on key factors such as emissions, technology deployment, macroeconomic indicators and international trade. In general, the simulations indicate that reductions in GHG emissions can be accomplished with limited economic adjustments, although impacts depend on the future availability of new low-carbon technologies.
Climate change policy involving a price on carbon would change the mix of power plants and the amount of water they withdraw and consume to generate electricity. We analyze what these changes could entail for electricity generation in the United States under four climate policy scenarios that involve different costs for emitting CO2 and different technology options for reducing emissions out to the year 2030. The potential impacts of the scenarios on the U.S. electric system are modeled using a modified version of the U.S. National Energy Modeling System and water-use factors for thermoelectric power plants derived from electric utility data compiled by the U.S. Energy Information Administration. Under all the climate-policy scenarios, freshwater withdrawals decline 2-14% relative to a business-as-usual (BAU) scenario of no U.S. climate policy. Furthermore, water use decreases as the price on CO2 under the climate policies increases. At relatively high carbon prices (>50/tonne CO2), however, retrofitting coal plants to capture CO2 increases freshwater consumption compared to BAU in 2030. Our analysis suggests that climate policies and a carbon price will reduce both electricity generation and freshwater withdrawals compared to BAU unless a substantial number of coal plants are retrofitted to capture CO2.
Thermoelectric power plants require significant quantities of water, primarily for the purpose of cooling. Water also is becoming critically important for low-carbon power generation. To reduce greenhouse gas emissions from pulverized coal (PC) power plants, post-combustion carbon capture and storage (CCS) systems are receiving considerable attention. However, current CO2 capture systems require a significant amount of cooling. This paper evaluates and quantifies the plant-level performance and cost of different cooling technologies for PC power plants with and without CO2 capture. Included are recirculating systems with wet cooling towers and air-cooled condensers (ACCs) for dry cooling. We examine a range of key factors affecting cooling system performance, cost and plant water use, including the plant steam cycle design, coal type, carbon capture system design, and local ambient conditions. Options for reducing power plant water consumption also are presented.
This paper examines the cost of CO(2) capture and storage (CCS) for natural gas combined cycle (NGCC) power plants. Existing studies employ a broad range of assumptions and lack a consistent costing method. This study takes a more systematic approach to analyze plants with an amine-based postcombustion CCS system with 90% CO(2) capture. We employ sensitivity analyses together with a probabilistic analysis to quantify costs for plants with and without CCS under uncertainty or variability in key parameters. Results for new baseload plants indicate a likely increase in levelized cost of electricity (LCOE) of ) or 23-39/MWh and 125/t CO(2) to ensure NGCC-CCS is cheaper than a plant without CCS. Higher costs are found for nonbaseload plants and CCS retrofits.
Coal-fired power plants account for nearly 50% of U.S. electricity supply and about a third of U.S. emissions of CO(2), the major greenhouse gas (GHG) associated with global climate change. Thermal power plants also account for 39% of all freshwater withdrawals in the U.S. To reduce GHG emissions from coal-fired plants, postcombustion carbon capture and storage (CCS) systems are receiving considerable attention. Current commercial amine-based capture systems require water for cooling and other operations that add to power plant water requirements. This paper characterizes and quantifies water use at coal-burning power plants with and without CCS and investigates key parameters that influence water consumption. Analytical models are presented to quantify water use for major unit operations. Case study results show that, for power plants with conventional wet cooling towers, approximately 80% of total plant water withdrawals and 86% of plant water consumption is for cooling. The addition of an amine-based CCS system would approximately double the consumptive water use of the plant. Replacing wet towers with air-cooled condensers for dry cooling would reduce plant water use by about 80% (without CCS) to about 40% (with CCS). However, the cooling system capital cost would approximately triple, although costs are highly dependent on site-specific characteristics. The potential for water use reductions with CCS is explored via sensitivity analyses of plant efficiency and other key design parameters that affect water resource management for the electric power industry.